A controllable or switchable pressure storage device of this type is used to ensure proper functioning of, or to improve the response characteristic of, hydraulic components in an engine, to which components oil pressure must be available in as short a time as possible in particular when starting the engine. This can for example be a hydraulic camshaft phaser or a supply unit for supplying oil under pressure to the camshaft bearing points in the cylinder head. Hydraulic camshaft phasers are described for example in the following publications of applicant: DE 20 2005 008 264 U1, EP 1 596 040 A2, DE 10 2005 013 141 A1, and WO 2006/039966. The demands on the pressurized oil supply stated here hold in particular for engines of vehicles having a start-stop system, or in engines in which, in hot idling operation, the supply of pressurized oil without a pressure storage device is not sufficiently ensured in all operating states.
In the German patent application originating from applicant and not yet published at the time of application, and having official file number 10 2009 054 052.0, a pressure storage device is disclosed that is placed in a hollow space inside a camshaft. On the basis of such an integrated construction, the required constructive space for a corresponding engine can be reduced in comparison with a design having a storage device situated separately, i.e. situated outside the camshaft.
An alternative embodiment of an integrated pressure storage device is described in the German patent application, also originating from applicant and not yet published at the time of application, having official file number 10 2010 063 390.9.